1. Field of the Invention
The present invention relates to a heat exchanger for heating a passenger compartment of a vehicle by carrying out heat exchange between air and hot water (engine coolant), to which an electric heat emitter is attached.
2. Description of Related Art
A heating heat exchanger to which an electric heat emitter is attached is disclosed in JP-A-63-203411 and JP-U-6-75819. According to this heating heat exchanger, the electric heat emitter is integrated with the heat exchanger to heat air by carrying out heat exchange between the air and hot water (engine coolant). In the heating heat exchanger, when the hot water temperature is low as in right after a vehicle engine starts, an electric current is supplied to the electric heat emitter. Then, the heat generated by the electric heat emitter radiates to the air through corrugated fins of the heat exchanger, and the air is heated.
However, according to the heating heat exchanger disclosed in JP-A-5-69732, because the electric heat emitter including a heat emitting element and electrode plates is brazed with a core portion of the heat exchanger, the electric heat emitter is exposed to a high temperature condition (about 600.degree. C., in case an aluminum brazing process is carried out). As a result, the electric characteristic of the heat emitter is deteriorated.
Further, according to JP-U-6-75819, the electric heat emitter is installed in a concave portion formed on an air downstream side surface of the plate fin, in a plate fin type heating heat exchanger. In this plate fin type heat exchanger, a cylindrical tube is mechanically expanded to connect to the plate fin. Therefore, a heat resistance at the connecting portion becomes large, thereby decreasing the heat conductive efficiency of the heat exchanger.
Further, the concave portion is additionally formed on the plate fin for installing the electric heat emitter, thereby increasing the manufacturing cost of the heat exchanger.